code: def get_start_end_idx(self):
      start_idx = self.data_parallel_rank * self.micro_batch_size
      end_idx = start_idx + self.micro_batch_size
      return start_idx, end_idx
  
file_path: NeMo/nemo/collections/nlp/data/language_modeling/megatron/data_samplers.py
imports: import abc
  from itertools import chain
  from typing import Optional
  import torch
  from nemo.utils import logging
label_desc: Use image node_id 1 for calling the MegatronPretrainingSampler obj's underlying member method code with example usage: obj.get_start_end_idx() and returns: start_idx,  end_idx